A portable terminal such as a mobile telephone, a Personal Digital Assistant (PDA) or a smart phone often has a rectangular flat shape in order to make it easier for the user to hold and operate. Therefore, the shape of the display screen is also often rectangular. However, the shape of contents, such as a webpage, that are displayed in the display screen does not always match the shape of the display screen, so in some cases the contents may not be displayed properly. For example, when contents that are long in the horizontal direction are displayed in a case such as illustrated in FIG. 1 where the display screen is a rectangular shape that is long in the vertical direction of the portable terminal, part of the contents are not displayed on the display screen.
To solve this kind of problem, there is a technique for controlling the display direction of the contents. More specifically, information on the face of the user of the portable terminal is acquired based on an image that is taken by a camera provided in the portable terminal. Moreover, the relative positional relationship between the orientation of the user's face and the orientation of the portable terminal is found. The orientation of information that is displayed on the display screen of the portable terminal is then set according to the found positional relationship.
However, in order to monitor whether there is a change in the direction of the user's face, power is constantly supplied to the camera, and image analysis is constantly performed, so power consumption becomes extremely large. In the case of the portable terminal, shortening the amount of time that the battery can be continuously used is not preferred. However, when an attempt is made to decrease the power consumption by simply reducing the frequency of taking images and performing image analysis, there is a problem in that the response becomes slow.
Namely, in the conventional display control in the portable terminal, the power consumption cannot be reduced.